This invention relates to a belt conveyor and in particular to a low profile belt conveyor.
Belt conveyors are used to convey numerous commercial and agricultural products such as coal, metal, metal ores, scrap materials, grains and the like. The conveyors typically comprise a frame, pulleys on opposite ends of the frame and a continuous belt that runs around the pulleys and along the length of the conveyor frame. The belt is in the form of a loop with an upper travel portion, which carries product on its upper surface, and a return lower travel below and generally parallel to the upper travel. Belt conveyors may be disposed substantially horizontally or may be disposed at an angle to horizontal to move product upwardly as well as laterally.
Most belt conveyors include one or more idler assemblies for supporting the belt from excessive sagging between the pulleys. Idler assemblies may be used to support both the upper and lower travel portions of the belt. The weight of product on the upper travel portion will typically cause the belt to sag in the middle along at least a portion of the length of the upper travel portion. Idler assemblies for the upper travel portion of belts are therefore typically trough or U-shaped to generally match the longitudinal sag in the belt. Idler assemblies for the lower travel portions of the belts are typically straight since the lower travel portion doesn""t carry product and does not sag like the upper travel portion.
Most idler assemblies for belt conveyors comprise idler rollers mounted on generally U-shaped idler frames that are secured on the top of the conveyor frame. A plurality of rollers are typically configured in a trough within the idler frame for supporting the upper travel of the belt. The idler assemblies are spaced along the length of the conveyor to provide a plurality of spaced apart supports for the belt. The idler rollers are typically mounted on axle and bearings assemblies so the rollers can freely rotate under the belt with little friction between the belt and the rollers. As is well known in the art, the rollers in such idler assemblies are prone to malfunction and are difficult to maintain and repair.
It is known to provide idler assemblies that include wear bars, instead of rollers, for supporting the belt as is disclosed in U.S. Pat. Nos. 4,789,056; 4,932,516; 5,799,780; and 5,826,703. The wear bars are made of a material having a relatively low coefficient of sliding friction with the conveyor belt. The use of such low friction wear bars eliminates moving parts from the idler assemblies and simplifies repair and replacement of the wear members, among other advantages. The idler assemblies disclosed in the patents include generally U-shaped frames so the idler assemblies can be retrofitted onto existing conveyors.
An improved belt conveyor is needed that is more compact and less expensive to manufacture. A conveyor is also needed that has improved mounting of low friction wear pads in the idler assemblies to facilitate maintenance, repair and replacement of the pads.
This invention provides an improved low profile belt conveyor having idler assemblies that use low friction slider pads for supporting the conveyor belt. The conveyor can be substantially horizontal or can be disposed at an angle to horizontal to carry product along the conveyor. The conveyor includes a frame having parallel side stringers, pulleys on opposite ends of the frame, and an endless belt for conveying product. It further includes at least one idler assembly having low friction slider pads on it for supporting an upper travel portion of the belt that carries product. The idler assembly is secured to the side stringers and forms a trough between the side stringers for the belt to fit into as it sags under the weight of the product. The trough is generally below the top of the frame so that the conveyor has a low profile that will conserve space and not interfere with other equipment or structural overhangs.
In a preferred embodiment of this invention, the slider pads are made of ultra high molecular weight polyethylene such as Tivar(copyright) 1000 material that is available form Solidur Plastics Company, Pittsburgh, Pa.
The slider pads are preferably mounted on trough shaped steel support plates that are secured to the top of the side stringers. The slider pads are bolted to the steel support plates through countersunk holes in the support pads and matching holes in the steel plates. The holes in slider pads and plates are preferably oversized to accommodate differences between the thermal expansion of the polymer slider pads and the steel plates.
Accordingly, it is an object of this invention to provide an impruved low profile belt conveyor that has idler assemblies with slider pads made of low friction material to support the conveyor belt.
It is a further object to provide a low profile belt conveyor that is more flexible in its positioning and use.
Another object of this invention is to provide a belt conveyor having low friction slider pads in its idler assemblies. Such slider pads have low coefficients of sliding friction with the conveyor belts and are wear resistant and durable. The improved slider pads eliminate moving parts in the idler assembly and therefore reduce maintenance. The material of the slider pads is also self-lubricating, resistant to attack by harsh chemicals, and exhibits essentially zero water absorption.
Other objects and advantages of this invention will be more fully understood and appreciated by reference to the following description of preferred embodiments and to the attached drawings.